Analysis of the Environmental and Safety Aspects of a Routine Utility Flare Using CFD

The CFD code C3d was used to investigate the operation of a routine utility flare at low and high gas firing rates in an oil field in Iraq. This code was developed for analysis of transient flares, enables the simulation of flare operation, and offers detailed estimates of the flame shape and the emissions produced. In this work, the numerical simulations included two flare gas rates, 9 t/h (2.5 kg/s) and 45 t/h (12.5 kg/s), under three crosswind conditions (4 m/s, 8 m/s and 14 m/ s) and using three stack heights (35 m, 45 m, and 55 m). The results of this work provided insights into flame shape and size, pollutant types and dispersion, and ground heat radiation levels from the flare. The safety analysis found that ground-level heat increases with higher flare gas rates and decreases with higher stack heights. The stack height of 55 m and the lower gas firing rate of 9 t/h were identified as the safest operating conditions as they provide lower ground level heat compared to the higher flare gas rate of 45 t/h. Likewise, environmental analysis showed that plume size increases with increasing flare gas rate, while pollutant dispersion intensifies with stronger crosswinds. When comparing the two gas firing rates, in the case of 9 t/h there was a smaller plume and less pollutant dispersion which illustrates the relatively lower impact on the environment.